The Mouth-to-Migraine Connection

Have you ever considered that the cause of your headaches could be in your mouth? Our mouths are full of bacteria, the majority of which are harmless. But when the balance tilts in favor of harmful bacteria, a host of problems can occur, including tooth decay, inflammation, and gum disease, as well as increased risk for cardiovascular disease, diabetes, and infections. Now, a new study reveals a possible additional side effect of oral bacteria—migraines!Woman holding tooth brush in front of eyes and applying tooth paste

The Link Between Migraines and Oral Bacteria

Nearly 38 million Americans suffer from migraines, but the exact cause of these debilitating headaches is unknown. Researchers have pinpointed a few dietary catalysts, such as wine, processed meats, chocolate, and dark leafy greens. What do these foods all have in common? High levels of nitrates.

Nitrates are naturally occurring chemical compounds in water, soil, and plants that oral bacteria convert to nitrites in the body. These nitrites can then been transformed into nitric oxide, which has been shown to boost blood flow and lower blood pressure, thereby improving cardiovascular health. For this reason, pharmaceutical drugs containing nitrates are often given to patients experiencing heart failure or chest pains. However, 4 out of 5 cardiac patients on nitrate-based drugs suffer from migraines as a side effect.

To test this connection, researchers from the Center for Microbiome Innovation at University of California, San Diego, collected data from the American Gut Project, described by lead author Antonio Gonzalez as one of the “largest crowd-sourced, citizen science projects in the country.”

woman with a head ache holding her head on a tableResearchers sequenced bacteria from 172 oral samples and 1,996 fecal samples collected from healthy participants who, at the start of the study, completed questionnaires to determine if they suffered from migraines or not. While types of bacteria were pretty much the same among migraine sufferers and those without migraines, the quantities of bacteria appeared to be very different.

An analysis of fecal samples showed that migraine sufferers had more genes that coded for nitrate, nitrite, and nitric oxide-related enzymes…and this difference was even more pronounced in oral bacteria.

This study helps increase our understanding of the role microbes play in migraines. However, researchers do not yet know if bacteria causes migraines, or migraines cause the increase in bacteria. Researcher Embriette Hyde, Ph.D. explains: “We know for a fact that nitrate-reducing bacteria are found in the oral cavity. We definitely think this pathway is advantageous to cardiovascular health. We now also have a potential connection to migraines, though it remains to be seen whether these bacteria are a cause or result of migraines, or are indirectly linked in some other way.” 

UCSD researchers next step is to split the migraine sufferers into two groups: one with migraines with aura (sensory disturbances) and one with migraines without aura. They hope to better ascertain how patterns in the dissemination of bacteria might affect migraine tendencies.